572 research outputs found

    Solar Energy Conversion by Thermal Destruction of Conductivity

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    A method is proposed for converting solar radiation directly to electrical energy in space by utilizing the change of state of a superconductor. Apparatus is described whereby intermittent exposure to a concentrated beam of solar radiation causes a magnetic shield to fluctuate between the superconductive state (zero permeability) and the normal state (unity permeability) with resultant flux changes converted to electrical energy by conventional induction methods. A thermal embodiment of Lexis\u27s law, akin to the back torque of a conventional generator or the counter current in the primary of a transformer, is postulated. Such a reaction is demanded by energy conservation principles, although in the present case it can be exerted only against an input of purely thermal energy. In a heat engine working between heat quantities represented by intercepted solar flux at the upper limit and the black cold of space at the lower limit, a theoretical thermal efficiency in excess of 99% is possible. In order to realize this phenomenal efficiency in a heat engine with a radiator of practical size, a closed compound cycle is proposed in which a portion of the power output is used to drive a refrigerator. By compounding the cycle the net thermal efficiency is reduced but the effectiveness of the system remains unchanged, provided only that a part of the output of the converter be utilized in the cooling of other cryogenic devices such as superconductive delay lines, lasers, IR sensors etc., the balance being available for general purposes. The heat extracted from all cryogenic equipment, including the converter itself, can then be radiated away at a temperature high enough to benefit from the fourth power law. A practical form of the converter is described, with particular reference to the problem of eddy-current losses, which are unusually severe at very low temperatures

    Remote measurement of turbidity and chlorophyll through aerial photography

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    Studies were conducted utilizing six different film and filter combinations to quantitatively detect chlorophyll and turbidity in six farm ponds. The low range of turbidity from 0-35 JTU correlated well with the density readings from the green band of normal color film and the high range above 35 JTU was found to correlate with density readings in the red band of color infrared film. The effect of many of the significant variables can be reduced by using standardized procedures in taking the photography. Attempts to detect chlorophyll were masked by the turbidity. The ponds which were highly turbid also had high chlorophyll concentrations; whereas, the ponds with low turbidity also had low chlorophyll concentrations. This prevented a direct correlation for this parameter. Several suggested approaches are cited for possible future investigations

    Personality and Injury Risk Among Professional Hockey Players

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    Background: Although much is known about risk for athletic injury, research on the roles of individual differences in personality and temperament on athletic injury has lagged. We hypothesized that professional athletes with high sensation-seeking and extraversion scores, and with low effortful control scores, would experience more injuries over the course of a season, would have more severe injuries, and would miss more total days of play. Methods: Prospective design with questionnaire report at time one and injury tracking throughout an 18-week athletic season. Setting: Professional hockey team in the United States. Participants: Eighteen professional hockey players (ages 21-33). Measurements: Players completed self-report personality (Sensation-Seeking Scale, Form V) and temperament (the Adult Temperament Questionnaire) measures. Quantity and severity of injury, as well as playing time missed, were tracked for 18 weeks. Results: On average, players experienced almost 6 injuries causing a loss of 10 playing days through the season. Those players scoring high on Boredom Susceptibility and Total Sensation-Seeking incurred more total injuries. Those scoring high on temperamental neutral perceptual sensitivity suffered more severe injuries. Conclusions: Athletes who suffered more injuries reported a preference for stimulating environments and boredom with non-stimulating environments. Injury severity was not correlated with sensation-seeking but was related to temperamental perceptual sensitivity. Implications for identification of injury-prone athletes, pre-injury training, and post-injury treatment are discussed

    French feminism: national and international perspectives

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    During the 1980s, the French media proclaimed the death of feminism, but although the 1970s women’s movement had demobilised, feminists were still active in issue-specific groups, in academia and within the institutions of the state. Paying careful attention to the difficulties associated with defining feminisms and national feminisms in particular, this article situates an analysis of French feminism since the 1980s in a context of growing international feminist dialogue and activism and a renewed debate about the meaning of feminism. It focuses on the question of separatism and on changing relations between theory and practice, asking how feminists can act for change and form effective coalitions with men and with other movements. It argues that feminism is plural and often fragmented and diffuse. Feminism is shaped by local social, economic, political and cultural factors and by exchanges of people and ideas, and any analysis of feminist theory and activism needs to take these into account

    Parental perceptions of barriers and facilitators to preventing child unintentional injuries within the home: a qualitative study

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    Background Childhood unintentional injury represents an important global health problem. Most of these injuries occur at home, and many are preventable. The main aim of this study was to identify key facilitators and barriers for parents in keeping their children safe from unintentional injury within their homes. A further aim was to develop an understanding of parents’ perceptions of what might help them to implement injury prevention activities. Methods Semi-structured interviews were conducted with sixty-four parents with a child aged less than five years at parent’s homes. Interview data was transcribed verbatim, and thematic analysis was undertaken. This was a Multi-centre qualitative study conducted in four study centres in England (Nottingham, Bristol, Norwich and Newcastle). Results Barriers to injury prevention included parents’ not anticipating injury risks nor the consequences of some risk-taking behaviours, a perception that some injuries were an inevitable part of child development, interrupted supervision due to distractions, maternal fatigue and the presence of older siblings, difficulties in adapting homes, unreliability and cost of safety equipment and provision of safety information later than needed in relation to child age and development. Facilitators for injury prevention included parental supervision and teaching children about injury risks. This included parents’ allowing children to learn about injury risks through controlled risk taking, using “safety rules” and supervising children to ensure that safety rules were adhered to. Adapting the home by installing safety equipment or removing hazards were also key facilitators. Some parents felt that learning about injury events through other parents’ experiences may help parents anticipate injury risks. Conclusions There are a range of barriers to, and facilitators for parents undertaking injury prevention that would be addressable during the design of home safety interventions. Addressing these in future studies may increase the effectiveness of interventions

    Mind your step: the effects of mobile phone use on gaze behavior in stair climbing

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    Stair walking is a hazardous activity and a common cause of fatal and non-fatal falls. Previous studies have assessed the role of eye movements in stair walking by asking people to repeatedly go up and down stairs in quiet and controlled conditions, while the role of peripheral vision was examined by giving participants specific fixation instructions or working memory tasks. We here extend this research to stair walking in a natural environment with other people present on the stairs and a now common secondary task: Using one's mobile phone. Results show that using the mobile phone strongly draws one's attention away from the stairs, but that the distribution of gaze locations away from the phone is little influenced by using one's phone. Phone use also increased the time needed to walk the stairs, but handrail use remained low. These results indicate that limited foveal vision suffices for adequate stair walking in normal environments, but that mobile phone use has a strong influence on attention, which may pose problems when unexpected obstacles are encountered

    Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

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    SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation

    Validation of a low-cost virtual reality system for training street-crossing. A comparative study in healthy, neglected and non-neglected stroke individuals

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    Unilateral spatial neglect is a common consequence of stroke that directly affects the performance of activities of daily living. This impairment is traditionally assessed with paper-and-pencil tests that can lack correspondence to real life and are easily compensated. Virtual reality can immerse patients in more ecological scenarios, thus providing therapists with new tools to assess and train the effects of this impairment in simulated real tasks. This paper presents the clinical validation and convergent validity of a low-cost virtual reality system for training street-crossing in stroke patients with and without neglect. The performance of neglect patients was significantly worse than the performance of non-neglect and healthy participants. In addition, several correlations between the scores in the system and in the traditional scales were detected.This study was funded in part by Ministerio de Educacion y Ciencia Spain, Projects Consolider-C (SEJ2006-14301/PSIC), "CIBER of Physiopathology of Obesity and Nutrition, an initiative of ISCIII" and the Excellence Research Program PROMETEO (Generalitat Valenciana. Conselleria de Educacion, 2008-157).Navarro, MD.; Llorens Rodríguez, R.; Noé, E.; Ferri, J.; Alcañiz Raya, ML. (2013). Validation of a low-cost virtual reality system for training street-crossing. A comparative study in healthy, neglected and non-neglected stroke individuals. Neuropsychological Rehabilitation. 23(4):597-618. https://doi.org/10.1080/09602011.2013.806269S597618234Allegri, R. F. (2000). Atención y negligencia: bases neurológicas, evaluación y trastornos. Revista de Neurología, 30(05), 491. doi:10.33588/rn.3005.99645Appelros, P., Karlsson, G. M., Seiger, Åke, & Nydevik, I. (2002). Neglect and Anosognosia After First-Ever Stroke: Incidence and Relationship to Disability. Journal of Rehabilitation Medicine, 34(5), 215-220. doi:10.1080/165019702760279206Baheux, K., Yoshizawa, M., & Yoshida, Y. (2007). Simulating hemispatial neglect with virtual reality. Journal of NeuroEngineering and Rehabilitation, 4(1). doi:10.1186/1743-0003-4-27Boian, R. F., Burdea, G. C., Deutsch, J. E. and Winter, S. H. Street crossing using a virtual environment mobility simulator.Paper presented at 3rd Annual International Workshop on Virtual Reality. Lausanne, Switzerland.Broeren, J., Samuelsson, H., Stibrant-Sunnerhagen, K., Blomstrand, C., & Rydmark, M. (2007). Neglect assessment as an application of virtual reality. Acta Neurologica Scandinavica, 116(3), 157-163. doi:10.1111/j.1600-0404.2007.00821.xBuxbaum, L. J., Ferraro, M. K., Veramonti, T., Farne, A., Whyte, J., Ladavas, E., … Coslett, H. B. (2004). Hemispatial neglect: Subtypes, neuroanatomy, and disability. Neurology, 62(5), 749-756. doi:10.1212/01.wnl.0000113730.73031.f4Buxbaum, L. J., Palermo, M. A., Mastrogiovanni, D., Read, M. S., Rosenberg-Pitonyak, E., Rizzo, A. A., & Coslett, H. B. (2008). Assessment of spatial attention and neglect with a virtual wheelchair navigation task. Journal of Clinical and Experimental Neuropsychology, 30(6), 650-660. doi:10.1080/13803390701625821Castiello, U., Lusher, D., Burton, C., Glover, S., & Disler, P. (2004). Improving left hemispatial neglect using virtual reality. Neurology, 62(11), 1958-1962. doi:10.1212/01.wnl.0000128183.63917.02Conners, C. K., Epstein, J. N., Angold, A., & Klaric, J. (2003). Journal of Abnormal Child Psychology, 31(5), 555-562. doi:10.1023/a:1025457300409Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). «Mini-mental state». Journal of Psychiatric Research, 12(3), 189-198. doi:10.1016/0022-3956(75)90026-6Fordell, H., Bodin, K., Bucht, G., & Malm, J. (2011). A virtual reality test battery for assessment and screening of spatial neglect. Acta Neurologica Scandinavica, 123(3), 167-174. doi:10.1111/j.1600-0404.2010.01390.xGupta, V., Knott, B. A., Kodgi, S., & Lathan, C. E. (2000). Using the «VREye» System for the Assessment of Unilateral Visual Neglect: Two Case Reports. Presence: Teleoperators and Virtual Environments, 9(3), 268-286. doi:10.1162/105474600566790Hartman-Maeir, A., & Katz, N. (1995). Validity of the Behavioral Inattention Test (BIT): Relationships With Functional Tasks. American Journal of Occupational Therapy, 49(6), 507-516. doi:10.5014/ajot.49.6.507Jannink, M. J. A., Aznar, M., de Kort, A. C., van de Vis, W., Veltink, P., & van der Kooij, H. (2009). Assessment of visuospatial neglect in stroke patients using virtual reality: a pilot study. International Journal of Rehabilitation Research, 32(4), 280-286. doi:10.1097/mrr.0b013e3283013b1cJehkonen, M., Laihosalo, M., & Kettunen, J. (2006). Anosognosia after stroke: assessment, occurrence, subtypes and impact on functional outcome reviewed. Acta Neurologica Scandinavica, 114(5), 293-306. doi:10.1111/j.1600-0404.2006.00723.xKatz, N., Ring, H., Naveh, Y., Kizony, R., Feintuch, U., & Weiss, P. L. (2005). Interactive virtual environment training for safe street crossing of right hemisphere stroke patients with Unilateral Spatial Neglect. Disability and Rehabilitation, 27(20), 1235-1244. doi:10.1080/09638280500076079Kim, D. Y., Ku, J., Chang, W. H., Park, T. H., Lim, J. Y., Han, K., … Kim, S. I. (2010). Assessment of post-stroke extrapersonal neglect using a three-dimensional immersive virtual street crossing program. Acta Neurologica Scandinavica, 121(3), 171-177. doi:10.1111/j.1600-0404.2009.01194.xKim, J., Kim, K., Kim, D. Y., Chang, W. H., Park, C.-I., Ohn, S. H., … Kim, S. I. (2007). Virtual Environment Training System for Rehabilitation of Stroke Patients with Unilateral Neglect: Crossing the Virtual Street. CyberPsychology & Behavior, 10(1), 7-15. doi:10.1089/cpb.2006.9998Kim, K., Kim, J., Ku, J., Kim, D. Y., Chang, W. H., Shin, D. I., … Kim, S. I. (2004). A Virtual Reality Assessment and Training System for Unilateral Neglect. CyberPsychology & Behavior, 7(6), 742-749. doi:10.1089/cpb.2004.7.742Kim, Y. M., Chun, M. H., Yun, G. J., Song, Y. J., & Young, H. E. (2011). The Effect of Virtual Reality Training on Unilateral Spatial Neglect in Stroke Patients. Annals of Rehabilitation Medicine, 35(3), 309. doi:10.5535/arm.2011.35.3.309Krakauer, J. W. (2006). Motor learning: its relevance to stroke recovery and neurorehabilitation. Current Opinion in Neurology, 19(1), 84-90. doi:10.1097/01.wco.0000200544.29915.ccMcComas, J., MacKay, M., & Pivik, J. (2002). Effectiveness of Virtual Reality for Teaching Pedestrian Safety. CyberPsychology & Behavior, 5(3), 185-190. doi:10.1089/109493102760147150Myers, R. L., & Bierig, T. A. (2000). Virtual Reality and Left Hemineglect: A Technology for Assessment and Therapy. CyberPsychology & Behavior, 3(3), 465-468. doi:10.1089/10949310050078922Peskine, A., Rosso, C., Box, N., Galland, A., Caron, E., Rautureau, G., … Pradat-Diehl, P. (2010). Virtual reality assessment for visuospatial neglect: importance of a dynamic task. Journal of Neurology, Neurosurgery & Psychiatry, 82(12), 1407-1409. doi:10.1136/jnnp.2010.217513Romero, M., Sánchez, A., Marín, C., Navarro, M. D., Ferri, J., & Noé, E. (2012). Utilidad clínica de la versión en castellano del Mississippi Aphasia Screening Test (MASTsp): validación en pacientes con ictus. Neurología, 27(4), 216-224. doi:10.1016/j.nrl.2011.06.006Rose, F. D., Brooks, B. M., & Rizzo, A. A. (2005). Virtual Reality in Brain Damage Rehabilitation: Review. CyberPsychology & Behavior, 8(3), 241-262. doi:10.1089/cpb.2005.8.241Schwebel, D. C., & McClure, L. A. (2010). Using virtual reality to train children in safe street-crossing skills. 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Influence of Virtual Reality Training on the Roadside Crossing Judgments of Child Pedestrians. Journal of Experimental Psychology: Applied, 11(3), 175-186. doi:10.1037/1076-898x.11.3.175Weiss, P. L. (Tamar), Naveh, Y., & Katz, N. (2003). Design and testing of a virtual environment to train stroke patients with unilateral spatial neglect to cross a street safely. Occupational Therapy International, 10(1), 39-55. doi:10.1002/oti.176Witmer, B. G., & Singer, M. J. (1998). Measuring Presence in Virtual Environments: A Presence Questionnaire. Presence: Teleoperators and Virtual Environments, 7(3), 225-240. doi:10.1162/105474698565686Wu, H., Ashmead, D. H. and Bodenheimer, B.Using immersive virtual reality to evaluate pedestrian street crossing decisions at a roundabout. Paper presented at 6th Symposium on appied perception in Graphics and Visualization. Chania

    Independent Risk Factors for Injury in Pre-School Children: Three Population-Based Nested Case-Control Studies Using Routine Primary Care Data

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    Background: Injuries in childhood are largely preventable yet an estimated 2,400 children die every day because of injury and violence. Despite this, the factors that contribute to injury occurrence have not been quantified at the population scale using primary care data. We used The Health Improvement Network (THIN) database to identify risk factors for thermal injury, fractures and poisoning in pre-school children in order to inform the optimal delivery of preventative strategies. Methods: We used a matched, nested case-control study design. Cases were children under 5 with a first medically recorded injury, comprising 3,649 thermal injury cases, 4,050 fracture cases and 2,193 poisoning cases, matched on general practice to 94,620 control children. Results: Younger maternal age and higher birth order increased the odds of all injuries. Children’s age of highest injury risk varied by injury type; compared with children under 1 year, thermal injuries were highest in those age 1-2 (OR = 2.43, 95%CI 2.23–2.65), poisonings in those age 2-3 (OR = 7.32, 95%CI 6.26–8.58) and fractures in those age 3-5 (OR = 3.80, 95%CI 3.42–4.23). Increasing deprivation was an important modifiable risk factor for poisonings and thermal injuries (tests for trend p#0.001) as were hazardous/harmful alcohol consumption by a household adult (OR = 1.73, 95%CI 1.26–2.38 and OR = 1.39, 95%CI 1.07–1.81 respectively) and maternal diagnosis of depression (OR = 1.45, 95%CI 1.24–1.70 and OR = 1.16, 95%CI 1.02–1.32 respectively). Fracture was not associated with these factors, however, not living in single-adult household reduced the odds of fracture (OR = 0.88, 95%CI 0.82–0.95). Conclusions: Maternal depression, hazardous/harmful adult alcohol consumption and socioeconomic deprivation represent important modifiable risk factors for thermal injury and poisoning but not fractures in preschool children. Since these risk factors can be ascertained from routine primary care records, pre-school children’s frequent visits to primary care present an opportunity to reduce injury risk by implementing effective preventative interventions from existing national guidelines
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